The general objective of this proposal is to gain a comprehensive understanding of inherited disorders of cellular transport resulting in renal aminoacidurias and melliturias. The underlying approach continues to be the application of biochemical techniques to delineate basic alterations of cellular function resulting from deranged genetic expression. Various model systems will be employed ranging from the intact animal to cellular and subcellular fractions. Aspects of renal tubule cell transport to be examined are: 1) brush border membrane structure and function; 2) developmental characteristics of amino acid and sugar transport focusing on regulation and control mechanisms; 3) the role of gammaglutamyl cycle in amino acid transport, and 4) the mechanism of cystinuria in stone-forming dogs as a model for human cystinuria. BIBLIOGRAPHIC REFERENCES: Reynolds, R. and Segal, S. Regulatory characteristics of amino acid transport in newborn rat renal cortex cell. Biochim. Biophys. Acta 426, 513-525, 1976. Goldmann, D.R., Schlesinger, H. and Segal, S. Isolation and characterization of the brush border fraction from newborn rat renal proximal tubular cells. Biochim. Biophys. Acta 419, 251-260, 1976.